A display device includes a primary display area which comprises a first display area and a second display area which is unique from the first display area, a control unit configured to display an image in the primary display area, an image signal generating unit configured to generate display data based on externally input image data for a single image. The image signal generating unit comprises a memory which stores display-position information indicating a display location of a first image displayed in the primary display area. The display data comprises first and second display data to be displayed in the first display area and the second display area, respectively. The first display data is generated based on the externally input single image data and the display-position information. The control unit is configured to cause a first image to be displayed in the first display area based on the first display data.